Lubricants and methods of preparing same



Patented June 26,

" UNITED STATES PATENT orrics LUBRICANTS AND METHODS OF PREPARING SAME Y I John G. McNab, Crawford, and Walter T. Watkins, Jr., Elizabeth, N. J., assignors to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 12, 1940, Serial No. 369,808

24 Claims. (Cl. 252-48) This invention relates to lubricants and methods of preparing same, and more particularlyto mineral lubricating oil compositions for use as crankcase lubricants for internal combustion engines, and especially for Diesel engines.

It is known that the addition of certain types of metal compounds to lubricating oils improves erate at relatively high temperatures such as high speed and heavy duty Diesel engines. It has also been suggested touse metal salts of alkylated phenol sulfides for improving the engine performance of lubricating oils, and in certain instances these compounds have been found to be substantially non-corrosive to alloy bearings of the type mentioned above.

It has now been found that these metal salts of alkylated phenol sulfides, which may also be called metal salts of aroxy sulfides, are not only non-corrosive improvers of engine performance in lubricating oils, but also have the surprising property of substantially reducing, if not entirely preventing, the corrosiveness of other type of metal compounds such as those mentioned above, which improve the characteristics of a mineral lubricating oil but tend to increase the corrosiveness thereof toward sensitive alloy bearings. Furthermore, these anti-corrosive sulfide compounds appear to cooperate with the other type of metal compounds in some way so as actually to enhance the engine performance characteristics of the lubricating oil compositions even more than could reasonably be expected from the mere addition of the separate addition agents. These and other objects and advantages of the invention will appear more clearly in the following more detailed description.

The relatively corrosive type of metal comlatum, sweater oil or other petroleum hydrocarbons, and also metal derivatives of either allphatic alcohols such as stearyl alcohol, cetyl alcohol, etc. or of aromatic alcohols, e. g., benzyl alcohol or of naphthenic alcohols, or other metal compounds such as the metal phenolates, metal,

enolates (derived from the enolic structure of ketones), metal sulfonates, sulfates and phosphates. The metals contemplated include aluminum, calcium, nickel, barium, magnesium, cobalt, chromium, lead, tin and their mixtures.

The amount of such corrosive metal compounds used will usually range between the approximate limits of 0.01% to 2.0% and generally about 0.1 %1.0% will give the best results. How much should be used will depend to some extent upon a number of factors such as the type ofmineral oil base stock, the type of metal compound being used and the severity of the operating conditions, as well as upon the type and amount of anticorrosive metal compound to be used. A series ofcorrosion and engine tests, to determine the optimum proportions with the particular materials to be used, may be run in the laboratory before marketing such lubricating oil compositions for commercial use.

The anti-corrosive metal compound to be used according to this invention may be considered in a general way to be a metal salt of an alkylated hydroxy aryl sulfide. A representative example of such a compound is the cobalt salt of hydroxy tertiary amyl phenyl sulfide. Broadly, these compounds may be considered as having the following general formula:

M-Y?rZz-Q R...

in which M is a metal; Y is either oxygen or a member of the sulfur family; Ar is an aromatic nucleus such as benzene or a condensed ring nucleus, e. g., naphthalene, anthracene, etc.; Z

is sulfur, selenium or tellurium; a: is an integer of' from 1-5, preferably 1 or 2; Q is an organic group which may be identical with the part of the compound which is on the left side of. the Z, or a group having a somewhat similar type of structure,'or it maybe a hydrocarbon group such as alkyl, e g., amyl, 'octadecyl, etc.; or aralkyl, e. g., benzyl; or aryl, e. g., tolyl etc.; and Rm represents one or more hydrocarbon groups, such as alkyl, or

' alkenyl, e.g., amyl, octyl, octenyl, etc.; or cyclo aliphatic, e. g., cyclo hexyl; or aralkyl, e.g., benzyl; or alkaryl, e. g., amyl phenyl; or various substituted derivatives thereof containing elements such as halogen, sulfur, nitrogen, oxygen,

phosphorus, etc., so long as these groupings do "other in a disulfide form, and also if there are a plurality of R groups each willrequire at least one bond connecting it to the aromatic nucleus Ar. It should also be DOintedout that as in the case of the specific cobalt compound illustrated above, a single bivalent metal atom may be con nected through Y atoms to two aromatic nuclei which may in turn be connected to the same or different Z atoms. The number and location of g the m tal linkageswill depend upon the valency of the metal and upon the proportions of the raw materials used in preparing the metal compounds.

These anti-corrosive metal compounds are usually made by first reactin a suitable phenolic compound such as an alkylated phenol with a sulfur halide, and the resulting product then reacted with a metal oxide or hydroxide or other suitable derivative. The amount of Z atom in the final product need not necessarily correspond to an'even integer; for example, analysis .of the compound may indicate 81.5, in which case it is likely that the product contains a mixture of compounds having a single sulfur linkage and other molecules having two sulfur linkages.

Various metals may be used in preparing these anticorrosive metal compounds; the following are representative examples: cobalt, calcium, barium, aluminum, zinc, magnesium, cadmium, tin, lead, chromium, manganese, and nickel, and although polyvalent metals, especially in groups 2,, 3 and 8 of the periodic table, such as those mentioned above, are preferred, monovalent metals such as sodium and potassium may also be used. Also, such complexes as ammonium or amino groups may be used in place of metal elements in these phenolate sulfides. v

The proportion of metal to non-metal in the anti-corrosive compound, may vary over a fairly wide range, due both to the fact that with various valencies the metal may combine with one to three or even more hydroxy aryl sulfide radicals, and to the fact that where there are two or more hydroxy groups present the metal may be used to replace only one of the hydroxyl hydrogen atoms. Furthermore mixtures of these various compounds may be prepared and used.

In the above described general formula, Y is preferably oxygen from practical considerations, although if desired it may also be sulfur, selenium or tellurium.

The aromatic nucleus Ar may be a phenyl group or it may be a polycyclic group such asin biphenyl, naphthalene, phenanthrene, anthracene, and the like.

Z is preferably sulfur, especially from the point of view of cost and availability, although selenium and tellurium can also be used if desired. Al-

though as indicated previously, a: is a number from 1-5, it should preferably be about 1-2, and sometimes best results are obtained by using products containing an amount of Z which is intermediate between whole numbers, for example 1.3 or 1.5. In such cases the products are mixtures as they may also 'be even when :cis a whole number. The value of :c, 'that is, the number of sulfur atoms, is determined by the quantity and type of sulfur halide used. Furthermore, sulfur dichloride appears usually to link the aryl nuclei with single sulfur bridges, whereas sulfur monochloride results in the formation of disulfide linkages.

matic nuclei, the alkyl groups-may appropriately be amyl, branched octyl groups (e. g. tetramethylbutyl) octadecyl, dodecyl, etc. With amyl groups as in the cobalt salt of tertiary amyl hydroxy phenyl sulfide, there are a total of 10 aliphatic carbon atoms present, and this is sufficient to give the desired oil solubility.

If the anti-corrosive metal compound is not symmetrical on both sides of the Z portion of the molecule, it is desirable that the radical Q should contain a suificient number of aliphatic carbon atoms to supplement those present in the radical, =AI'Rnn, to impart to the total metal compound a sufficient oil-solubility for the purposes desired.

The metal salts of alkylated aroxy sulfides are preferably obtained from phenolic compounds which are readily prepared by alkylation of simple phenols or which may be obtained by extraction of high boiling petroleum oil. One common method of alkylating henols is to condense them with olefins, the reaction being catalyzed by such agents as activated clay, hydrogen chloride, sulfuric acid, phosphoric acid, or an active metal halide. For example, phenol may be alkylated with diisobutylene or with tertiary .amylene obtained from petroleum refinery gases, to make disiobutyl phenol (or perhaps more properly called tetramethylbutyl phenol), or paratertiary amyl phenol, or the phenol may be alkylated by condensing it with chlorinated wax or with olefins derived by dehydrogenating parafiin wax or dehydrochlorinating chlorinated wax. Similarly, isohexyl phenol, tertiary butyl phenol, diamyl phenol, and the like may be prepared. Alkylated phenols may be obtained also by extraction of certain petroleum stocks, particularly those obtained during cracking operations, with caustic soda followed by acidification of the alkaline extract with a weak mineral acid.

Such inorganic substituents as maybe desired in the alkylated phenols are introduced by any well-known method. For example, alkyl chlorophenols may be prepared by direct controlled chlorination of the alkyl phenol, or by chlorinating the phenols before alkylation. Similarly, nitro groups may be introduced by direct nitration and these may be reduced to amino groups, if desired.

After'the phenols have been alkylated and then converted into corresponding sulfides by reaction with either sulfur monochloride or sulfur dichloride, for example, they are then converted into corresponding metal derivatives as by first reacting with metallic sodium in alcohol, or with sodium hydroxide, and then converting the resulting sodium salt into the corresponding salt of the desiredmetal by reacting the sodium salt with the chloride, nitrate, or other suitable inorgamc salts of the desired metal. In some cases In these formulas R has the same meaning as explained in connection with the general formula pounds of these hydroxy aryl sulfides function as corrosion inhibitors. It may be that they act as antioxidants to retard the formation of corrosive products in the oil, that they exert a pacifying effect on metal surfaces to render them resistant to attack by corrosive materials, or that certain of them (such as the ammonium, amino or alkali metal derivatives) serve as buflers because of their alkaline nature. However, the invention is not to be limited by any explanation of the possible mechanism of the corrosion preventing eifect.

The amount of the anti-corrosive metal compounds to be used should be about 0.1-2.0%. preferably about 0.2-1.0% in the finished lubricating oil. The exact amount for optimum results will depend partly upon the particular type of anti-corrosive metal compounds used, as well as upon the type and amount of corrosive metal compounds used and upon other factors such as the severity of the operating conditions to which the lubricating oil will be exposed, and the mineral oil base stock itself.

The lubricating oil base stock for this invention may be a mineral oil distillate or blend and may contain a residual oil, or it may be a frac- 'tion" resulting from various physical and chemical refinery treatments, such as solvent extraction, precipitation, etc. Since one advantage of this invention is that it makes feasible the employment of normally lesssatisfactory mineral oils by use of the hereinbefore'described addition agents, no strict rule can be laid down for the choice of the mineral oil base stock. However, the oil should possess 'the viscosity and volatility characteristics required for the service l contemplated and it must also be a satisfactory solvent for the several addition agents. For the lubrication of medium or high speed Diesel engines, for which this invention has special advantages, the lubricating oil base, stock should have a minimum A. P. I. gravity of about a minimum flash point of about 300 F., and a viscosity of about 40-95 seconds Saybolt at 210 F. For the lubrication of ordinary gasoline engines or the spark ignition type, the lubricating oils should preferably also have a viscosity index of about 50 or over. The lube 011 base stock may be.naphthenic, paraflinic, or mixed base, or it may be a synthetic lubricating oil, for instance as made by polymerization of low molecular .weight, e. g. gaseous olefins, or by cracking, hydrogenation and other chemical processes. In addition to the twov types of metal compounds to be added according to the present invention, other addition agents may be used such as fatty oils, dyes, pour depressors, heat they tend to become corrosive under certain con-' ditions in which the lubricating oil is used.

The following examples will serve to illustrate typical methods of preparing these compounds:

EXAIVIPLE 1 COBALT SALT 0F HYDROXY TERTIARY AMYL PHENYL SULFIDE A solution of the sodium salt of hydroxy tertiary amyl phenyl. sulfide was prepared by reacting 7.7 grams mol) of sodium dissolved in 150 cc. of absolute ethyl alcohol with 60 grams 6 mol) of hydroxy tertiary amyl phenyl sulfide dissolved in cc. of absolute alcohol.

A solution of 23 grams 0%; mol=21.7 grams) of anhydrous cobalt chloride in 250 cc. of absolute ethyl alcohol was added with agitation causing the mixture to turn brown. The alcohol was stripped oil and the brown residue-was agitated with a light solvent naphtha (boiling range naphthenic base lubricating oil having a Saybolt viscosity of about 55 seconds at 210 F., such as is suitable as a crankcase lubricant for Diesel 7 engines. 1

A EXAMPLE 2 BARIUM SALT or HYDROXY DIISOBUTY'L PHENYL SULFIDE Diisobutylene was condensed with phenol, using stannic chloride and dry hydrochloric acid gas as catalysts, to prepare diisobutyl phenol. Three mols (618 grams) of diisobutyl phenol which had been recrystallized from naphtha were dissolved in 1200 grams of chloroform, and a solution of 2.25 mols (232 g.) of sulfur dichloride (SC12) in 300 grams of chloroform was added gradually with stirring, care being taken to keep the reaction temperature between 20 and 25 C. Following this step the mixture was heated on a water bath and refluxed for two hours. The solvent was then stripped ofi. The recovered hydroxy diisobutyl phenyl sulfide was found to contain an average of 1.41 atoms of sulfur per molecule.

One mol (456 grams) of the above sulfide was dissolved in 3000 cc. of benzene and the solution placed in a reaction vessel equipped with a condenser having a trap for removing water. A total of 321 grams (315 g.=1 mol) of barium hydroxide octahydrate, Ba(H) 2.8H2O were added (in four equal portions) to the solution which was then heated for 26 hours under reflux, ,any evolved water being trapped out. 'The reaction mixture was then filtered and the solvent stripped oif, leaving a solid residue which could be pulverized to a fine yellow powder. This was found to be soluble in mineral lubricating oils. The yield of barium salt was 540 grams, or 91% of the theoretical yield.

The effect of adding these anti-corrosive metal salts of alkylated hydroxy phenyl sulfides to lubricating oils containing corrosive metal addition agents is shown in the following data ob- 0.25%. I These two blended oils were then compared as to corrosiveness toward copper-lead bearings and cadmium-silver bearings, the test conducted in the Underwood corrosion apparatus for 5 hours at 325 F. Tests were also made with blends of the same oil which contained various concentrations of both the sulfide and the phenolate. The test results are given in the accompanying Table I.

I TABLE I 5-hour Underwood corrosion tests at 325 F. Weight losses, expressed in milligrams, are for 2 Cu-Pb half bearings and for 2 C'd-Ag half bearings.

Per cent addition Bearing wt. loss,

agent mg. 'lcst No.

Ba salt 1 Co salt Cu-Pb Cd-Ag 0. 25 0.0 526 l, 326 0. 25 0. 25 109 l 0. 25 0. 5 64 3 0. 2 0. 5 62 l 0. l 0. 5 l9 2 barium diisobutyl phenolate. l Cobalt salt of tertiary amyl hydroxy phenyl sulfide.

It will be readily seen that the barium diisobutyl phenolate renders the oil very corrosive toward both types of bearings but that when the cobalt phenol sulfide salt is also added the corrosion is greatly reduced.

EXAMPLE 4 Blends of the cobalt salt of tertiary amyl hydroxy phenyl sulfide alone and with barium diisobutyl phenolate in a naphthenic base oil (the same I as in Example 3) were compared with the oil itself as to behavior in a single-cylinder Caterpillar Diesel engine. The oils were rated according to the condition of the engine after a certain number i of hours of running. The results are given in the accompanying Table II. It should be observed that the higher the numerical rating demerits the worse the condition of the engine or its parts.

TABLE II Tests in single cylinder Caterpillar engine Demerits of individual parts Test Hours Ovetr-all Oil treated on pis on test demerit Ring SGLS 1 Cargg Oll grooves bon nigh filter l g 110 l. 3. 1 l. 86 3. 4 2. 17 l. 5 2 Nuphthemc 011 A 242 1.96 4. 3 2. 5s 3. 9 2. 92 2.0 4 2 Oil A+0.5% cobalt salt 6O 1. l8 5 3 Oil liq-0.5% cobalt salt +0.2.s% barium salt a Q 8 39 5 2 l Cleanliness of ring slits grooves. lands and sides.

1 Cobalt salt of tertiary amyl hydroxy phenyl sulfide.

3 Barium salt of diisobutyl phenol.

tained from corrosion tests and from tests made in Diesel engines.

. EXAMPLE 3 The cobalt salt of hydroxy tertiary amyl phenyl sulfide was dissolved in a naphthenic base lubricating oil in the concentration of 0.5%. In another portion of the same oil, barium diisobutyl phenolate 1 was dissolved in the concentration of Barium salt of phenol which has been alkylated with diisobutylene.

EXAMPLE To a naphthenic base SAE 30 motor oil there was added a mixed aluminum-calcium soap of acids obtained in the oxidation of sweater oil. Blends were also made of this soap compounded oil with, in one case, a calcium salt of tertiary amyl hydroxy phenyl sulfide and, in the other,

' with the barium salt of diisobutyl hydroxy phenyl disulflde. These three oils were all compared as regards corrosiveness toward cadmium silver and copper-lead bearings with the results presented in Table In. The particularcorrosion test in this instance involved spinning bearing sections in the heated oil while air was passed through. After intervals of 1, 3, and 5 hours the bearings were removed and weighed. The tabulated results indicate that both'the sulfurcontaining calcium and the barium compounds reduced the corrosion markedly and that the calcium compound proved somewhat superior in this respect to the barium.

1 Salt of tertiary amyl hydroxy-phenyl sulfide.

EXAMPLE! A blend of 0.2% nickel oleate and 0.5% of the cobalt salt of tertiary amyl hydroxy phenyl sulflde was prepared in a naphthenic base lubricating oil. This blend was compared with the oil Team: 111 S. 0. D. bearing corrosion tests at 325 F.

Wt. losses per sq. cm. area, mg.

on 011 One hour 3 hours 5 hours No.

Gil-Pb Od-Ag Gil-Pb Cd-Ag Ou-Pb Cd-Ag 1 Base oil+0.25'7 Al-Ca soap 32 26 77 137 147 294 2 No. 1+1 calciumsalt 1 o 2 o 17 1 3 N0. 1+1 0 barium Shit 0 0 43 3 126 82 1 Salt of tertiary amyl hydroxy phenyl sulfide. Salt of diisobutyl hydroxy phenyl disulflde.

EXAMPLE 6 alone in an 84-hour test conducted in a Hercules Diesel engine under severe operating conditions. Similarly a blend of the cobalt salt in a naphthenic oil' was compared with the oil itself. From the results given in Table V it will be seen that the blend of nickel soap and the cobalt salt greatly improved the engine performance of the lubricating oil, the demerit being only 78% of that for the oil alone. For comparison, the blend containing only the cobalt salt had a demerit rating of 88% of thatfor the oil alone.

TABLE V 84-hour tests in Hercules Diesel engine Test No. Test No. Test No. Test No. 1 2 3 4 Oil tested Per cent Oil tested Per cent of ref. of ref.

Naph- Naph- Oil A+0.57 thenic gkfij fi thenic cobalt salt-{ oil B oil A 0.2 %Ni oleate Overall demerit J. 1. 95 1.71 as 2.14 1. 68 78 Individual demerits:

Combustion chamber. 2. 42 3. 00 v 124 3. 33 3. 25 98 Sludge 89 l. 86 98 1. 94 l. 83 94 Valves 1. 70 1. 64 97 l. 72 l. 72 100 Piston skirts 0. 83 0. 1.08 0. 69 Crankshaft 00 0. 50 50 2.00 0. 50 25 Rings and grooves 2. 48 l. 75 2. 61 1. 63 63 l Cobalt salt of tertiary amyl hydroxy phenyl sulfide.

Wilma where M is a metal, Y is a member of the righthand side of group 6 of the Mendeleeif Periodic Table of Elements, Ar is an aromatic nucleus, Z is a member of the sulfur family, a: is an integer of from 1 to 5, Q is an organic group, R represents a hydrocarbon group, and m is an integer indicating the number of R groups, said lubricant also containing a small amount of an oil soluble metal salt of an acidic organic compound.

2. A lubricant comprising a mineral oil base stock, a small amount of an oil soluble metal salt of the reaction product of an alkylated hydroxy aromatic compound with a sulfur halide, and a small amount of an oil-soluble metal salt of an acidic organic compound.

3. A lubricating oil composition comprising a mineral oil base stock containing dissolved therein a small amount of an oil-soluble metal salt of an acidic organic compound, said metal salt being adapted to improve the engine performance of said mineral oil base stock but normally tending to promote the corrosiveness thereof toward alloy bearings of the copper-lead, cadmium-silver type, and also a small amount of an oil soluble polyvalent metal salt of an alkylated hydroxy aryl sulfide adapted to make the lubricating oil com-,

position non-corrosive to such alloy bearings.

4. Composition according to claim 2, in which the corrosive compound is a metal derivative of an organic compound selected from the group consisting of fatty acids, naphthenic acids, alcohols, phenols, ketones, and hydrocarbons.

5. A lubricating oil composition comprising a major proportion of a mineral oil base stock, and a small amount of an oil soluble metal salt having substantially the general formula where M is a divalent metal, Y is oxygen or sulfur, Ar is an aromatic nucleus, R is an alkyl or substituted alkyl group having at least 4 carbon atoms, and :c is 1-5, and a small amount of an oil soluble metal salt of an acidic organic compound.

6. A lubricating oil composition comprising a major proportion of a mineral lubricating oil base stock having a minimum A. P. I. gravity of about 15, a minimum flash point of about 300 F., and a viscosity of about 40-150 seconds Saybolt at 210 F., containing dissolved therein about 0.01- 2.0% of'a metal soap and about 0.1-2.0% of a metal salt of an alkylated hydroxy phenyl sulfide.

'7. Composition according to claim 6, in which the sulfide is a salt of a divalent metal.

8. Composition according to claim ,6, in which the sulfide is a salt of cobalt.

,9. Composition according to claim 6 in which the sulfide is the salt of an alkaline earth element.

10. A lubricating oil composition comprising a major proportion of a mineral oil base stock, a small amount or an oil soluble metal phenolate, and" a small amount of an oil soluble metal salt of a hydroxy aryl sulfide having substantially the general formula where M is a metal, Ar is an aromatic nucleus, R is an alkyl or substituted alkyl group having at least 4 carbon atoms, and a: is1-5.

11. A lubricating oil composition comprising a major proportion of a mineral lubricating 011 base stock having a minimum A. P. I. gravity of about a minimum flash point of about 300 F., and a viscosity of about 40-150 seconds SaybOlt at 210 F., containing dissolved therein about 0.1-

, 1.0% of a metal phenolate and about 0.1-1.0%

of a metal salt of an alkylated hydroxy phenyl sulfide.

12. Composition according to claim 11, in which the sulfide is a salt of a divalent metal.

13. Composition according to claim 11, in which the sulfide is a salt of cobalt.

14. Composition according to claim 11, in which the sulfide is the salt of an alkaline earth element.

15. A lubricating oil composition especially adapted for lubrication of Diesel engines, which comprises a major proportion of a mineral lubricating oil base stock having a minimum A. P. I. gravity of about 15, a minimum flash point of about 300 F., and a viscosity of about 40-95 seconds Saybolt at 210 F., containing dissolved therein about 1.0% of nickel oleate, and a sufficient amount, between the approximate limits of 0.1 and 1.0% of a cobalt salt of tertiary amyl hydroxy phenyl sulfide, which makes the lubricating oil composition non-corrosive to sensitive alloy bearings. v

l6. Composition according to claim 1 in which said second metal compound is a, member of the class consisting of metal sulfonates, metal sulfates and metal phosphates.

17. Composition according to claim 2 in which the said second metal compound is a member of the class consisting of metal sulfonates, metal sulfates and metal phosphates.

18. Composition according to claim 3 in which the said first metal compound is a member of the class consisting of metal sulfonates, metal sulfates and metal phosphates.

19. Composition according to claim 3 in which the said first metal compound is an alkaline earth sulfonate.

20. A liquid lubricating oil for severe service internal combustion engines comprising mineral lubricating oil containing a small proportion of metal compound of a phenol thioether in quantity sufiicient to control development of corrosive conditions without imparting substantial visthe class consisting. of alkali metals and heavy metals.

23. A mineral lubricating 011 containing. asmall stock, a. small amount of an oil-soluble metal salt proportion between about 0.5% and 2.0% of an of the reaction product of an alkylated hydroxy oil-soluble metal salt of an alkylated polyphenol aromatic compound with a sulfur halide, and a sulfide, and a small proportion in the order of 1% small amount of an oil-soluble metal salt of an of oil-soluble metal detergent soap of saponiflable 5 acidic organic compound. organic acids. JOHN G. MCNlAB.

24. A lubricant comprising a mineral oil base v WALTER T. WATKINS, JR. 

